{"id":262450,"date":"2023-06-16T20:25:35","date_gmt":"2023-06-16T18:25:35","guid":{"rendered":"https:\/\/climatescience.press\/?p=262450"},"modified":"2023-06-16T20:25:38","modified_gmt":"2023-06-16T18:25:38","slug":"new-evidence-that-polar-bears-survived-1600-years-of-ice-free-summers-in-the-early-holocene","status":"publish","type":"post","link":"https:\/\/climatescience.press\/?p=262450","title":{"rendered":"New evidence that polar bears survived 1,600 years of ice-free summers in the early Holocene"},"content":{"rendered":"\n
\"\"
Polar Bear walking along the shores of Hudson Bay. Canada<\/figcaption><\/figure>\n\n\n\n

<\/p>\n\n\n\n

From polarbearscience<\/a><\/p>\n\n\n\n

New evidence<\/a>\u00a0indicates that Arctic areas with the thickest ice today probably melted out every year during the summer for about 1,600 years during the early Holocene (ca. 11.3-9.7k years ago), making the Arctic virtually ice-free. As I argue in\u00a0my new book<\/a>, this means that polar bears and other Arctic species are capable of surviving extended periods with ice-free summers: otherwise, they would not be alive today.<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

Money quote<\/a>:<\/strong> Here we show marine proxy evidence for the disappearance of perennial sea-ice in the southern Lincoln Sea during the Early Holocene, which suggests a widespread transition to seasonal sea-ice in the Arctic Ocean.<\/em> [Detlef et al. 2023: Abstract]<\/p>\n\n\n\n

Last Ice Area<\/a> and Lincoln Sea<\/a><\/p>\n\n\n\n

An illustration of the\u00a0Last Ice Area<\/a>\u00a0in the Arctic, which is currently covered in perennial ice (2-4m thick) that does not melt out every summer (Moore et al. 2019) from the press release for\u00a0a paper<\/a>\u00a0by Newton and colleagues (2021):<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

The Lincoln Sea discussed in the new paper is withing the LIA, between Greenland and Ellesmere Island, as shown below.<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

Wikipedia image<\/p>\n\n\n\n

The short animation below shows sea ice thickness from 1979-2022 in the Arctic at the height of summer within the Last Ice Area was ca. 2.5-4.0m thick<\/a>, which is thinner and less extensive than it was in the 1980s (when it was 4-5m thick or greater). In other words, perennial ice is not gone yet.<\/p>\n\n\n\n

\n

Loss of thicker September sea ice from 1979 to 2022…

Note that I have masked out sea ice < 1.5 meters in order to emphasize the decline of the (relative) thicker ice. Data from PIOMAS. You can compare this animation with a more realistic version here: https:\/\/t.co\/qXpJKsAzX9<\/a> pic.twitter.com\/Ki6vSuXNkT<\/a><\/p>— Zack Labe (@ZLabe) October 11, 2022<\/a><\/blockquote>